<blockquote>My gloss on it is that this is at best a minor part, though it figures in.</blockquote>

I think that, even if this is a minor part of the reasoning for those who (unlike me) believe in the danger, it could easily be the best, most consensus* basis for an explicit deletion policy. I'd support such a policy, and definitely think a secret policy is stupid for several reasons.

*no consensus here will be perfect.